I tend to do small summaries of the main points in the chapters before I get into the thumbnailing, usually 1-2 sentences per scene. Just enough to have it in memory long enough for my imagination to fill in dialogue, transitions, etc.
Ex:
[morning] Bikkel the clown wakes up and gets ready for another round of scheduled birthday gigs. Bikkel, bored out of his mind, wishes something interesting would happen before leaving his house.
Bikkel chats with some old friends and then grabs the train to his first gig, Bikkel arrives at the location after some personal monologue and gets off the train.
Bikkel the Clown explodes.
[End Chapter]
After I've got all that down, it's usually in memory and I never really have to look at it again. How well this works, though, depends on the person, and maybe your ability to improv a bit.